Reservoir systems, such as petroleum reservoirs, contain fluids such as water and various types of oil. The different recovery processes which are used for oil production from the reservoir may be classified as primary, secondary or tertiary recovery processes.
In a primary recovery process, the reservoir's energy and natural forces are used to produce the hydrocarbons contained in the reservoir fluid, such as oil and gas. Only a small fraction of the original-oil-in-place (OOIP) may be recovered by the primary recovery methods. That is, the average recovery is generally about 10-20% of the OOIP. In order to increase the production of oil from subterranean reservoirs, a variety of supplemental (secondary and/or tertiary) recovery techniques may be employed. In a secondary recovery process, energy is introduced into the reservoir by injection, e.g., of water or gas, to facilitate increased recovery. An additional 10-30% of OOIP over the primary recovery process may be obtained. A tertiary recovery process, which generally follows a secondary recovery, may provide for recovery of an additional 5 to 20% of the OOIP over the secondary recovery process. The most widely used secondary recovery technique is waterflooding, which involves the injection of water into the reservoir. Waterflood processes may be more economical than other oil recovery processes, which makes them attractive. A waterflood recovery process is referred to as improved oil recovery (IOR) process.
An enhanced oil recovery (EOR) process can be a tertiary recovery process or a secondary recovery process. The different EOR techniques may provide economical means for achieving recovery of an incremental amount of, e.g., the oil that can be produced from a reservoir after conventional primary or secondary production processes have been applied. Examples of EOR processes include, but are not limited to, polymer and surfactant flooding.
The methods and systems disclosed herein provide for determining whether a reservoir is a candidate for a waterflood process or an EOR process. Also, the methods and systems disclosed herein provide for determining the feasibility of a waterflooding and/or an EOR process for application in a reservoir and to recommend a specific injection scheme. In addition, the methods and systems disclosed herein provide an easy-to-use system for predicting the performance of a waterflooding process in a reservoir, and may be used at an early stage of planning the reservoir exploitation process. Methods and systems for predicting the performance of a polymer flooding technique versus a waterflooding technique in a reservoir also are provided.